Here we examine lens performance and depth of field from f/1.4 through f/11. Live View was used to establish focus precisely on a rock at the center of the frame because autofocus was way off, as usual.

Please note that many of the crops are unsharp at wider apertures because they are not within the zone of sharp focus (depth of field). So this example is instructive in at least three ways:

How image quality in the zone of sharp focus improves with stopping down.

Vignetting behavior.

How depth of field improves with stopping down, how well defined the image is, and whether the edges and corners are reputable or not.

A full aperture series is shown for each crop (click to view).

Vignetting series

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